Resin composition for form panel, and lightweight form panel

Abstract

To provide a resin composition for a form panel capable of solving the problems such that in construction using concrete, plywood panels which are lightweight and capable of sawing and nailing are frequently used from points of handling and it is difficult to reuse them multiple times, so they are incinerated, thus, there is a strong demand for a form panel and a composition therefor having handling properties equivalent to those of the plywood panels, capable of repeated use and having recyclability in view of CO2 reduction and SDGs.SOLUTION: A polypropylene resin, a biomass filler, and an inorganic filler are melted and mixed, and a melt tension of the obtained resin composition at 190°C is adjusted to 10 mN to 100 mN, and an MFR measured under conditions of a temperature of 190°C and a load of 10 kg is adjusted to 2 to 15. With this, a concrete form panel that has lightness equivalent to that of plywood and handling performance, can be used repeatedly, and maintains sufficient product rigidity can be obtained.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition for concrete formwork panels, which contains a polypropylene resin, a biomass filler, and an inorganic filler as main components, and to a formwork panel produced using the resin composition. [Background technology]

[0002] When constructing a concrete building, concrete formwork panels are essential materials, and currently, plywood made from imported wood is used. However, after using these wooden formwork panels 2-3 times, they become difficult to use any more due to the adhesion of cement and damage caused by the impact when peeling them off. Currently, unusable wooden formwork panels are transported to incinerators and incinerated. There is a strong demand for reducing CO2 emissions from the perspective of protecting the global environment, and it has become important to develop a concrete formwork panel that can replace plywood in line with the ideas of the SDGs. A formwork panel that meets this requirement should be reusable 10-15 times or more, and should be recyclable and remade into a formwork panel after use. Formwork panels made of polypropylene resin or its composite materials have been proposed as an alternative to wooden formwork panels, but there are many other characteristics required of formwork panels in addition to recyclability, and the reality is that no formwork panel meets these requirements.

[0003] The characteristics required for form panels are: (1) they must be a large product, but light enough to be carried by one person; (2) they must be rigid enough to withstand the weight of concrete; (3) they must have impact strength to withstand the impact when removing the form panels; (4) they must be able to be sawed in the same way as wood; (4) they must be able to be nailed and have the ability to hold nails; (5) they must have a smooth surface; (6) they must have minimal adhesion of concrete; (7) they must be able to be used repeatedly 10 to 15 times or more; and (8) they must be recyclable and turned back into form panels.

[0004] Although there are several prior patent documents relating to resin concrete formwork panels, none of them satisfy all of the various required characteristics. In particular, there has been a strong demand for formwork panels and materials (compositions) therefor that have handleability (lightweight, sawing ability, nailing ability) and reusability (reusability and impact resistance therefor) equal to or greater than that of the widely used plywood.

[0005] Patent Document 1 discloses a "concrete formwork panel with a specific gravity of 0.8 or less, which is manufactured by adding 0.4% by mass or more of a foaming agent to 100% by mass of a molding material consisting of 46-52% by mass of thermoplastic resin mainly composed of polypropylene, 33-38% by mass of wood flour with an average particle size of 50-300 μm, and the remainder as secondary materials, and extruding the mixture." However, since no consideration was given to repeated use or recycling to return the panel to a concrete formwork panel, there were problems such as low impact strength and breakage when the panel was removed. Furthermore, since no melt tension improver was used, the range in which wood flour and the like can be used was very narrow and limited, and there were problems such as recycling being very difficult. Patent Document 2 discloses a "high-strength panel using a polypropylene composition containing 10 to 60% by weight of paper powder and / or wood powder and 0 to 40% by weight of talc powder." However, What is disclosed is simply an extruded concrete panel, which is difficult to saw and nail and is therefore technically different from lightweight extruded foam concrete panels intended as a plywood replacement.

[0006] To replace plywood, a product needs to have the same thickness and rigidity as a plywood panel, so polypropylene resin alone is insufficient in terms of elasticity. Therefore, it is essential to improve the elasticity by adding a filler. On the other hand, to maintain the same handling properties as plywood (lightness, sawing, nailing), foam molding is essential. However, when filler is added, the melt tension of the resin drops significantly, making sufficient foam molding difficult due to bubble breakage and gas escape. After extensive research into a lightweight concrete formwork panel that can replace plywood and overcome this contradictory phenomenon, we discovered this technology. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2019-130861 A [Patent Document 2] Japanese Patent Application Publication No. 07-108582 Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved is to find a form panel that has the same handling performance (lightness, sawing ability, nailing ability) as plywood concrete form panels, but also has the opposing high product rigidity, i.e., a form panel that can be reused repeatedly and is far superior to plywood in accordance with the ideas of the SDGs, and a material (composition) for such a form panel. [Means for solving the problem]

[0009] They discovered that by melt-kneading polypropylene resin, biomass filler, and inorganic filler, and adjusting the melt tension of the resulting composition to 10 mN to 100 mN at 190°C and the MFR measured under conditions of 2 to 15 at a temperature of 190°C and a load of 10 kg, and then extruding and foaming the resulting pellets, it is possible to produce a concrete formwork panel that has the lightness and handling properties equivalent to plywood while maintaining sufficient product rigidity.

[0010] As the polypropylene-based resin in the present invention, commercially available polypropylene resins are If necessary, a high tensile strength polyolefin resin or a melt tension improver may be added. Examples of melt tension improvers include acrylic modified PTFE, acrylic resins, and long chain branched polyolefin resins. The composition obtained by adding biomass filler and inorganic filler to this polypropylene resin must have a melt tension of 10 to 100 mN at 190°C, and an MFR of 2 to 15 measured under conditions of a temperature of 190°C and a load of 10 kg. If the melt tension is 10 mN or less, foam molding becomes difficult due to cell breakage and gas escape. If the melt tension is 100 mN or more, heat generation becomes large, the resin temperature becomes too high, the foaming agent decomposes quickly, and foam molding becomes difficult, and the biomass filler may be burned. If the MFR is 2 or less, the viscosity is too high, so heat generation becomes large, making foam molding difficult. If the MFR is 15 or more, the melt tension becomes low, making foam molding difficult due to cell breakage and gas escape.

[0011] The proportion of the polypropylene resin in the resin composition in the present invention is 40 to 70 wt%. If the proportion of the polypropylene resin is less than 40 wt%, not only is it difficult to sufficiently foam the resin composition, but the impact resistance strength of the formwork panel is reduced, making it difficult to repeatedly use the panel. If the proportion of the polypropylene resin exceeds 70 wt%, the rigidity of the formwork panel is insufficient, making it impossible to use the formwork panel.

[0012] Biomass fillers include wood powder, bamboo powder, cellulose powder, etc., and have an average particle size of 30 to 500 μm, preferably 50 to 400 μm. The ratio of the biomass filler to the resin composition is 10 wt% to 60 wt%. If it is less than 10 wt%, the rigidity of the form panel is insufficient, and if it exceeds 60 wt%, foam molding becomes difficult and the impact strength of the form panel decreases, making it difficult to use the form panel repeatedly.

[0013] Examples of inorganic fillers include mica, talc, sericite, glass flakes, graphite, kaolin, calcium carbonate, silica, titanium oxide, alumina, magnesium hydroxide, aluminum hydroxide, barium sulfate, wollastonite, glass fiber, potassium titanate fiber, magnesium oxysulfate, etc., and among them, talc and mica are preferred. The proportion of inorganic filler in the resin composition for formwork panels is 0 to 40 wt%. If it exceeds 40 wt%, it becomes difficult to achieve uniform foaming and the impact strength of the concrete formwork panel decreases, making repeated use difficult.

[0014] Acid-modified polypropylene is a polypropylene molecule into which an unsaturated carboxylic acid has been introduced. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, and sorbic acid. Examples of derivatives of the unsaturated carboxylic acids include acid anhydrides, esters, amides, imides, and metal salts. Examples of the derivatives of the unsaturated carboxylic acids include maleic anhydride, itaconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, acrylamide, maleic acid monoamide, and maleimide. Among these, unsaturated dicarboxylic acids and their derivatives are preferred, and maleic acid is particularly preferred. The amount of the additive is 0.5 to 3 parts by weight per 100 parts by weight of the resin composition for concrete formwork panels. If the amount is less than 0.5 parts by weight, the interface between the resin and the biomass filler is not sufficiently modified, and the effect of suppressing gas scattering and promoting uniform foaming, as well as the effect of improving the strength and rigidity of the formwork panel, are insufficient. If the amount of the additive exceeds 3 parts by weight, the interface improvement effect is saturated, and no further effect is expected, which is economically disadvantageous.

[0015] The form panel needs to be foamed to reduce its weight, and the foaming method is a normal polypropylene extrusion foaming method. Among them, the Cerca method is preferable. The amount of the foaming agent used is 0.3 to 0.8 parts by weight based on 100 parts by weight of the resin composition for the concrete form panel. If the amount is less than 0.3 parts by weight, the foaming is insufficient, the form panel becomes heavy, and the product surface smoothness and nailing performance become insufficient. If the amount is more than 0.8 parts by weight, large cavities are likely to form inside the form panel, The nails will easily fall out and the panel will be easily broken when it is peeled off from the concrete, making it difficult to reuse the panel. Also, the elastic modulus will be low, resulting in insufficient rigidity of the panel. Effect of the Invention

[0016] By using the resin composition of the present invention, the above problems can be solved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A resin composition consisting of polypropylene resin, biomass filler, and inorganic filler was used, and by controlling the melt tension and MFR of the resin composition within a specific range, the desired lightweight, reusable concrete formwork panel was realized. EXAMPLES

[0018] Table 1 shows the composition used in this experiment. The polypropylene resins used were five types with MFRs of 0.5, 1.9, 2.4, 5.0, and 10. The high-tensile PP used was Waymax manufactured by Japan Polypropylene, with MFRs of 1.3 and 8.3. Furthermore, the melt tension improvers used were Metablen A-3000 (improver (1)) and A-1050 (improver (2)) manufactured by Mitsubishi Chemical. The biomass fillers used were wood powder (200μ), cellulose powder (80μ), and bamboo powder (300μ); the inorganic fillers used were talc (5μ) and mica (50μ). The acid-modified polypropylene used was Hardlen H-1000P, a maleic acid grafted polypropylene manufactured by Toyobo MC.

[0019] The components shown in Table 1 were dry-blended, then kneaded using a twin-screw kneader to produce pellets for extrusion. The pellets obtained were then dried at 110°C for 24 hours, after which a foaming agent was dry-blended and a concrete formwork panel (concrete panel) 12 mm thick, 600 mm wide, and 1800 mm long was produced by extrusion foam molding, and evaluated as a formwork panel. Polythrene EE515 (manufactured by Eiwa Chemical Industry Co., Ltd.), a master batch of sodium bicarbonate, was used as the foaming agent. The evaluation results are shown in Table 2.

[0020] Formwork panel molded product 1 and formwork panel molded product 2 were produced using compositions having melt tensions and MFRs within the claimed ranges of Examples 1 and 2, respectively. The formwork panels produced by extrusion foam molding were uniformly foamed and satisfied all of the required performance requirements, such as surface smoothness, nailing performance, and product rigidity. In addition, the formwork was peeled off with a crowbar and used repeatedly more than 10 times without any problems.

[0021] Formwork panel molded product 3 was made using the composition of Comparative Example 1, which had a melt tension lower than the claimed range, and had insufficient foaming due to cell breakage, etc., which resulted in poor nailing performance and surface smoothness, making it difficult to use as a lightweight formwork panel. In other words, it is clear that in order to improve the rigidity of the product, it is necessary to maintain high melt tension, which is reduced by the biomass filler or inorganic filler that is filled in.

[0022] Formwork panel molding product 4 was made using the composition of Comparative Example 2, which had a low melt tension and a higher MFR than the claimed range. Both the melt tension and melt viscosity were low, so the foaming gas escaped, making extrusion foam molding difficult, and a lightweight formwork panel could not be obtained.

[0023] Formwork panel molded product 5 was produced using the composition of Example 3, whose melt tension and MFR were within the claimed range. The formwork panel molded by extrusion foam molding had uniform foaming and satisfied all the required performances, such as surface smoothness, nailing performance, and product rigidity. In addition, the formwork was peeled off with a crowbar and used repeatedly more than 10 times without any problems.

[0024] The molded product 6 was made using the composition of Comparative Example 3, which contains a large amount of polypropylene resin and a small amount of biomass filler and inorganic filler, and because the amount of filler was small, the surface of the molded panel was wavy due to sink marks, resulting in insufficient smoothness, and the product rigidity (elastic modulus) was significantly insufficient. In addition, the MFR of the composition was too high, resulting in insufficient durability, and the product was broken after about six repeated uses.

[0025] The molded panel 7 was made using the composition of Comparative Example 4, which has high melt tension and low MFR. When the melt tension is too high, the extruder generates intense shear heat, the resin temperature rises, and the foaming agent decomposes quickly, making it difficult to perform foam molding and to manufacture the molded panel. Furthermore, the high temperature caused significant burning of the wood powder. From this result, it can be seen that in order to obtain a good molded panel, it is not enough to have a high melt tension, but there is an optimal range.

[0026] Formwork panel molding 8 was made using the composition of Comparative Example 5, which contains a small amount of polypropylene resin-based resin and a large amount of biomass filler and inorganic filler. Because the amount of filler was too large, the melt tension was small, and as a result, gas escape was severe, making extrusion foaming difficult, and a formwork panel could not be obtained.

[0027] The molded panel 9 was made by adding 1.5 parts by weight of foaming agent, which is more than the claimed range, to the composition of Example 1. The amount of foaming gas was too much, and large cavities were generated inside the molded panel, which caused the nails to easily fall out and limited the number of times it could be used repeatedly to about two times. The elastic modulus was also insufficient. This shows that in order to manufacture a molded panel that meets the purpose, the amount of foaming agent added must be limited to a certain range.

[0028] [Table 1]

[0029] [Table 2]

Claims

1. A resin composition for concrete formwork panels, which is a composition consisting of polypropylene resin, biomass filler and inorganic filler, and has a melt tension of 5mN to 100mN at 190°C and an MFR of 2 to 15 measured under conditions of a temperature of 190°C and a load of 10kg.

2. 2. A resin composition for use in a concrete form panel, comprising the polypropylene resin according to claim 1 and a high tensile strength polyolefin resin and a melt tension improver.

3. The resin composition according to claim 1 or 2 is a resin composition for a concrete form panel, which comprises 40-70 wt% of a polypropylene resin, 10-60 wt% of a biomass filler, and 0-40 wt% of an inorganic filler.

4. A resin composition for a concrete form panel, comprising 100 parts by weight of the resin composition according to claim 1, 2 or 3 and 0.5 to 3 parts by weight of an acid-modified polypropylene added thereto.

5. A concrete form panel produced by adding 0.3 to 0.8 parts by weight of a foaming agent to 100 parts by weight of the resin composition according to claim 1, 2, 3 or 4, and extruding and foaming the composition.

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